High-performance light emitting diode backlight driving system for large-screen liquid crystal display

A high-performance light emitting diode backlight driving system is proposed for large-screen liquid crystal display. The proposed system consists of a boost converter for power factor correction (PFC) and an active-clamp converter for dc-dc power conversion. With coupled inductors and simple passive components, the proposed PFC circuit minimises the switching losses by reducing the reverse-recovery current. The active-clamp converter operates under zero-voltage switching for the power switches and its output rectifier is composed of a current doubler and a synchronous rectifier for reducing conduction loss. The proposed backlight driving system is analysed and its design consideration is discussed in detail. Experimental results for a 300 W (3.3 V/90 A) prototype at a constant switching frequency of 100 kHz are presented to verify the analysis and the performance of the proposed system.